TW201713410A - Grinding rolls for ore and method for obtaining maximum efficiency of grinding rolls - Google Patents

Abstract

Description of grinding rolls for ore (1) composed of: two motors (6,6'), one mobile roller (3), one fixed roller (2), hydraulic cylinders (4) and feeding column (5). The grinding rolls (1) being provided with a means for controlling efficiency configured for making ongoing measurements and adjustments of their components aiming at reaching the maximum efficiency of the machine. A method for obtaining maximum efficiency of grinding rolls (1) is also described, which has the following steps: (i) determining the zero GAP; (ii) determining a set point that is equal to the optimum working point of the grinding rolls; (iii) automatic handling of pressure until the set point is reached.

Description

Grinding roll for ore and method for obtaining maximum efficiency of grinding roll

The invention consists of a grinding roll for iron ore and a method for maximizing the efficiency of the grinding roll.

This invention relates to abrasive rolls for iron ore having a means for controlling efficiency and a method set to maximize the efficiency of the grinding. In the ore granulation process, the grinding rolls are extremely important equipment. The granulation process involves the steps of comminution, coagulation, and pellet combustion. This comminution step is responsible for the fragmentation of the ore, which is responsible for particle formation. The grinding rolls in question are used in the first step (ie, the ore comminution step). A grinding roll is a relatively simple device consisting of two rolls supported by a roller bearing, one of which is fixed and the other moved; two electric motors, which are responsible for the torque Transfer to the rolls; a hydraulic cylinder responsible for forcing the moving roller against the fixed roll; and a feed column configured to evenly distribute the ore between the rolls. The grinding rolls operate as follows: the ore is guided in a feed column whose function is to distribute the material evenly between the rolls. The rollers rotate in opposite directions to force the material through the opening (gap) defined between the two structures until the ore reaches the compression zone. The compression zone is the zone in which the ore is repressed or depressed. It begins with a portion above and between the two rolls, and the pressure increases to the maximum point at the centerline of the two rolls. The hydraulic cylinders are responsible for forcing the moving roller against the fixed roller to comminute the material in the compression zone (see Figures 1 and 2 of the drawings). In the most advanced technology, in order to make better use of the grinding rolls, the components of the grinding rolls are adjusted to achieve a better performance of the machine for a given working condition. A solid stop is mounted on the machine to delimit the free mobility of the moving rolls. The stopper prevents the rollers from colliding with each other to avoid wear or breakage of the components, and the "zero clearance" (which is the shortest distance between the two rollers) is set by manual adjustment of the stopper. The test is completed in one of the first forms of adjustment and holds different variables and results, defining a zero gap and initial working pressure. Under normal conditions, the press operator will not change the operating pressure or clearance, and there is one of the operator's disturbances only for special reasons, including low feed, low performance or some operational limitations of the equipment. The level of the ore column is set by the engineer responsible for the zone (ie, controlling the ore height present on the grinding roller) and it should be the highest possible value with a lower standard deviation. Once this value is set, it is determined to maintain this value during its operation. The pressure during the procedure is kept constant and as high as possible so that the torque of the rolls is up to the maximum. However, if the pressure is too high, the moving roller will be driven to the stopper and will not cause energy to be transferred from the rollers to the ore crushing operation. In other words, there is an optimum hydraulic working pressure that would cause the roller to remain stationary on the stopper and, depending on the conditions, begin to squeeze rather than crush the material. Too little pressure causes the material to pass between the rolls without being crushed. The rotation of the rolls is variable depending on the ore column level. The entire PLC logic of the frequency inverter is programmed to keep the column level constant. However, since the rotation of the rolls is affected by other factors present in the program, they become unstable, requiring constant adjustment in the apparatus. The operator controls the pressure with his hand. In addition to knowledge of press operation, the operator is required to understand the ore morphology, humidity level, particle size, roll wear, pneumatic spring pressure, column level, roll rotation and zero clearance. With all this information, the operator can correctly set the hydraulic pressure for that particular condition. After a few minutes, if any of the variables change, the settings will no longer be optimal and another setting will be required. This means that once a machine setting is made by an operator, the control also shows that it is susceptible to human error. State of the art technology includes grinding rolls, which have components for automatically controlling the opening between the rolls, however, the grinding rolls included in the most advanced technology cannot analyze all the variables, make them equal, and take adequate measures to re-make them Lead to the best point. Document US 5,154,364, filed on September 28, 1990, discloses a technique for the comminution of food grains such as soybeans, wheat, corn, and the like. This technique allows for adjustments to one of the distances between the rolls for protection and better efficiency, depending on what we intend to perform. This adjustment is made by an electric motor coupled to one of the grinding rolls and one of the sensors responsible for measuring the distance between the rolls. The motors coupled to the grinding rolls are configured to increase and decrease the distance between the rolls in order to achieve the necessary mode of operation for the type of grain to be comminuted. Grains that require more particle breakage require a shorter distance between the rolls, while grains that require less particle breakage require a longer distance between the rolls. The technique disclosed in U.S. Patent 5,154,364 also allows manual adjustment of the distance between the rolls. These adjustments are made by performing a lever that moves a male and female thread to push the moving roller against the fixed roller. The technique disclosed in US Pat. No. 5,154,364 allows to avoid accidents that damage the rollers when an electric motor is used as needed to adjust the distance between the grinding rollers. The distance between the rolls is also adjusted to become the most feasible for the procedure, thus achieving one of the safety and efficiency improvements of the grinding rolls. However, the technique mentioned is not applicable to grinding rolls for ore because it does not take into account the variables involved in ore comminution, including: feed column level, morphological characteristics, rotation of the rolls, and use of grinding rolls. Other factors inherent in the ore crushing process. Thus, it can be inferred that the state of the art technology does not include any automatic control techniques configured to maximize the efficiency of the grinding rolls by virtue of the control of all variables present in the ore crushing operation. There is also no method of configuring the maximum efficiency of the iron ore grinding rolls.

The object of the present invention is an iron ore grinding roll having a control member for maintaining its maximum efficiency throughout the operating time. The object of the present invention is also an iron ore grinding roll that is more economical, more efficient, and less susceptible to human error than conventional grinding rolls. It is also an object of the present invention to maximize the delivery of finished products having superior quality compared to finished products delivered using conventionally controlled grinding rolls. Finally, the object of the invention is also a method for obtaining the maximum energy efficiency of a grinding roller. The object of the present invention is achieved by an ore grinding roller, which is composed of two motors, a fixed roller coupled to a reduction gear and the motor through a universal shaft, and a moving roller. Arranged in the same manner but with one degree of freedom for radial movement; a hydraulic cylinder, which is mounted on the roller bearing housing, perpendicular to the radial face of the moving roller, to force the moving roller against the fixed roller; And a feed column disposed perpendicular to the two rolls directly above the gap defined between the two structures; the ore grinding roll has a member for controlling efficiency. The object of the invention is also achieved by a method for obtaining the maximum efficiency of the grinding rolls. The method consists of (i) determining a zero gap; (ii) determining a set point equal to one of the optimum operating points of the grinding rolls; (iii) treating the pressure until the set point is reached.

The present invention relates to a grinding roll 1 for iron ore having a member for controlling efficiency. The invention also relates to a method for controlling the efficiency of a grinding roll 1 for ore. The grinding roll 1 for ore consists of machines used in the comminution process of different types of ore (Fig. 1). The grinding roller 1 is composed of two rollers 2, 3 which are mounted on a roller bearing, the two rollers 2, 3 being a fixed roller 2 and a moving roller 3; two electric motors 6, 6' Is responsible for transmitting torque to the rollers 2, 3; the hydraulic cylinder 4, which is responsible for pushing the moving roller 3 against the fixed roller 2, thereby grinding the ore passing between them; and a feed column 5 It evenly distributes the ore between the rolls 2, 3 (Figs. 1 and 2). The components mentioned are responsible for the efficiency of the machine and the final product results. Therefore, one of these components is required to automatically monitor and adjust. The most advanced technology consists of two types of controls. A first form of control over the definition of pressure, and a second form of control over the gap between the rolls 2, 3. However, the two forms of control do not involve all components that affect the efficiency of the machine and, additionally, the first form of control mentioned is performed by an operator and is therefore susceptible to human error. The grinding roll 1 of the present invention is composed of a member for controlling efficiency, which is responsible for automatically adjusting and controlling all the components involved in the pulverizing process which affect the efficiency of the grinding roll 1. The means for controlling efficiency are set to directly or indirectly control virtually all of the variables involved in the shredding procedure. The shortest distance allowed between the first controlled variable system rolls 2, 3. This distance is referred to as zero clearance and consists of a safety clearance established by providing a physical stop within the machine. The sole function of the stopper is to prevent the moving roller 3 from colliding with the fixed roller 2, thereby damaging the surface of the rollers 2, 3 or even the grinding roller 1 more severely. The operating distance between the second controlled variable system rolls 2, 3, i.e., the gap between the rolls 2, 3 during operation of the machine. This distance is referred to as the operating clearance and is transmitted through the distance adjustment performed by the hydraulic cylinder 4 such that the high pressure tends to close the operating gap and the reduced pressure tends to open the operating gap (Fig. 3). Since the operation gap is controlled by the treatment of a third variable (hydraulic), the operating gap is controlled indirectly by the press 1 by a variable. The third controlled variable is the torque provided by the motors 6, 6'. By definition, a component of force that is disposed perpendicular to the axis of rotation of a given object is a portion that effectively causes one of the objects to rotate about its own axis. The torque of the rolls 2, 3 can be measured by the energy motors 6, 6' that need to perform work when attempting to break the ore. The torque can be measured by the current consumed by the motors 6, 6', ie the more electric power the motor 6, 6' consumes, the more it is transferred to the ore crushing (the electrical energy is converted into mechanical work, and the use of more electrical energy leads to more execution) The higher the power of the work). In other words, a large consumption of energy implies a higher comminution rate. The torque control is given by the other two variables (i.e., the pressure generated by the hydraulic cylinder 4 and the rotation of the rollers 2, 3). Since the torque is dependent on the other two variables that control the change, the torque is indirectly controlled by the press. The fourth controlled variable is the pressure that is performed by the hydraulic cylinder 4. The hydraulic pressure generated on one zone is restored to the force generated by the moving roller 3 against the fixed roller 2. The pressure is adjusted as the operating clearance is intended to be working, i.e., a lower operating clearance requires high pressure, while a larger operating clearance requires lower pressure. The rotation of the fifth controlled variable system rolls 2, 3 functions to regulate the flow of material passing between the rolls 2, 3. The rotation of the rolls 2, 3 is controlled by the motors 6, 6' and according to the amount of material present in the feed column 5 at a given time. The sixth controlled variable is the level 8 of the feed column 5, i.e., the amount of ore found in the feed column 5 at a given time. The level 8 rises or falls based on the difference between the ore mass flow in the inlet port at the upper portion of the feed column 5 and the ore flow through the press 1. Look for one of its stable levels because the balance point of the system remains the same and there is no change in the best point of work. In addition, the risk of the column 5 overflowing, the press 1 being overloaded, or becoming temporarily unusable in the absence of material inside the feed column 5 should be avoided. The only variable that is not controlled by press 1 is the ore moisture, which is one of the properties of the feedstock and is from the previous procedure and is defined as the weight percent of the material. When the humidity percentage is too high, the friction between the surfaces of the rolls 2, 3 and the treated material is reduced, so that the rolls 2, 3 stop crushing the material and begin to extrude the material, ie, the material "slides" through the gap instead of Being crushed. In other words, when the ore is wet, the rolls 2, 3 cannot drag the material to the compression zone 9. This causes the rotation of the rolls 2, 3 to increase to maintain the column level and, in addition, also causes a reduction in the operating clearance and reduced comminution under the squeezing effect of the material in the compression zone, thereby substantially reducing the motor power. Except for all the inconveniences mentioned, the extrusion of the material causes premature wear of the rolls, which is caused by the relative movement between the surface of the stud pin and the material (which is undesirable). The jagged marks on the surface of the pin are similar to the "shark teeth" that authenticate the movement of the ore. These variables are controlled and uncontrolled variables found in the pulverization process using the grinding roll 1. These variable interactions are known, i.e., a modification of one variable causes a change in other variables. To better understand the interaction between variables, the following shows a table showing the effect of each change of a given variable on the residual variables of the program. Table 1 - Effect and Causes of Program Variables * Increase in pressure causes torque to increase up to a certain limit. After the "best" point, the pressure increase causes the torque to drop, and then, when the roller is fixed to the stopper, the torque remains constant or even increases the pressure, and the excess force (which is not used to process the material) is transferred to the press Chassis; * Once on the stopper, the pressure increase does not affect the rotation or clearance; ** there is also an ideal point for rotation. Lower rotation does not necessarily result in a higher torque; *** This also applies to the operating clearance. It may be desirable to reach a point of equilibrium and above or below this point the torque will decrease; note that an increase in the column will cause an increase in torque and operating clearance. The rotation of the rolls 2, 3 controls the amount of crushed ore, i.e. the mass of material passing between the rolls 2, 3. The rotation of the rolls 2, 3 is increased according to the increase of the level 8 of the feed column 5, that is, one of the set points above the feed column 5 requires one of the rolls 2, 3 to rotate faster to increase in a given The flow of material that is processed by the press 1 at all times. On the other hand, lowering one of the set points 8 in the feed column 5 requires a slower rotation of one of the rolls 2, 3 to reduce the mass flow of material processed by the press 1 at a given time. Efficiency control minimizes the loss of the conventional system and continuously adjusts the program parameters to convert the maximum amount of electrical energy into comminution work. As previously discussed, the operating clearance is established by the pressure generated by the hydraulic cylinder 4. In a normal operation, a high pressure tends to reduce the operating gap, and a decrease in pressure tends to increase the operating gap. The pressure generated by the hydraulic cylinder 4 also affects the torque, and the value of the torque (to a certain limit) is proportional to the amount of pressure generated by the hydraulic cylinder 4 (Fig. 4). However, as the operating clearance is reduced, the flow of material passing between the rolls 2, 3 is also reduced, and when this occurs, the rotation between the rolls 2, 3 is automatically increased so that the level in the feed column 5 8 remains stable. However, the increased rotation of the rollers 2, 3 (starting at a certain point) has a negative image of the torque (Table 1 and Figure 5). In short, the higher the pressure generated by the hydraulic cylinder 4 within a certain value, the lower the operating clearance and the higher the compressor torque. Paradoxically, when the operating gap is reduced, the flow of material processed by the press 1 is limited, causing the level 8 in the feed column 5 to increase, and when this occurs, the press 1 automatically reacts to determine the roll. One of the rotations of 2, 3 increases, which in turn reduces the torque of the press 1 from a certain point. The complex relationship between the variables is plotted in Figure 6 to show the quadratic equation for torque and operating clearance (for the same feed rate). The apex of the parabola shown in Figure 6 is the point at which the press 1 operates with the highest possible torque. This point is called "optimal working point 15" and is found between areas A and B of the figure. In zone A, the torque is affected by the high rotation of the rolls 2, 3, while in zone B the torque is affected by the low pressure generated by the hydraulic cylinder 4. In the optimum operating point 15, the torque is the maximum, which implies a high comminution rate. The optimum operating point 15 varies depending on the nature of the material being processed, for example by the humidity and natural quality of the ore processed at a given time. Based on the ratio between the variables described above, a set point equal to one of the optimal operating points shown in Figure 6 is sought for the operational gap. In other words, the operating gap is adjusted for maximum torque. Each feed rate, humidity, roll surface setting, column level, and hydraulic-pneumatic spring pressure requires an efficiency curve, so finding one of the system set points is difficult and complicated. The optimum working point 15 is determined as follows: First, an operational clearance control should be implemented according to the pressure, ie, an operating clearance set point is defined (1 mm difference between the recommended maximum and minimum values (example: 5 mm minimum and 6) Mm max)), therefore, the pressure is modulated to achieve the target. Subsequently, the operating clearance should be changed from a wide opening to a minimum clearance, reminding that the feed should be constant, thus plotting curve 6. When the working gap is lower than the defined one (set point), it may mean that the material humidity increases, resulting in a reduction in the friction ratio between the material and the rolls 2, 3 and also in the compression zone. The operation gap is closed, so the behavior mentioned above occurs. Likewise, the increased rotation reduces the torque. On the other hand, when the reversal occurs, the working gap tends to be larger than the defined one (set point), so the rotation is slowed down and the roller is open, so a pressurizing stroke is necessary to increase the torque. After determining the optimal operating point 15, the efficiency control member changes the system pressure based on the determined settings to maintain the set point of the operating gap. In the same feed range, in order to achieve the determined set point, the press 1 automatically adjusts the pressure provided by the hydraulic cylinder 4. When the set point is found, the pressure is kept constant. Thus, the grinding roller 1 achieves an effective control system that is intended to maximize the transfer of energy for the comminution process and the larger amount of processed material for a period of time. It should be noted that in order for the operating gap to operate at different set points within a defined degree of freedom, the zero gap must have the lowest possible value, otherwise the press stopper prevents the rollers 2, 3 from being defined as one of the operating gaps that are too small. An optimal working point is 15 operations. In its preferred configuration, the grinding roll 1 for ore is operated with the following values: one close to zero, one zero gap, one between 3 mm and 12 mm, and 75% of its maximum power. One torque between 98%. In view of the considerations described herein, in addition to the grinding roll 1, the invention also consists of a method for obtaining the maximum efficiency of the grinding roll 1. The method consists of the following steps: i) establishing a minimum distance between the moving roller 3 and the fixed roller 2 using a solid stopper; ii) determining one of the operating gap setting points, which coincides with the optimal working point 15 Iii) controlling the pressure provided by the hydraulic cylinder 4 until the operating clearance set point is reached; alternatively, the method may include a fourth step of increasing the pressure generated by the hydraulic cylinder 4 until the operating clearance is about to become low The set point is determined in step ii. In this case, the method can be defined as follows: i) using a solid stopper to determine a minimum distance between the moving roller 3 and the fixed roller 2; ii) determining a set point for operating the gap, the set point is The optimum working point 15 coincides; iii) controls the pressure provided by the hydraulic cylinder 4 until the operating clearance set point is reached; iv) once the operating clearance reaches the set point, the pressure is no longer changed. Therefore, it is inferred that the present invention achieves the goal of being more economical, effective, and less susceptible to human error than conventional grinding rolls and allowing one of the higher quality products to be finished. A higher economy is achieved by lower specific power consumption by machine and also by system automation (which does not require a full-time operator to adjust the rotation and torque of the press 1). Achieving higher efficiency by automatically controlling one of the possible smashes for a higher time. Further, the higher quality of the finished product of the press of the present invention comes from the fact that the grinding roll 1 of the present invention is capable of delivering a finished product having a finer particle size than that required for granulation of ore. Having described some examples of preferred embodiments of the present invention, it should be noted that the scope of protection granted by this document includes all other alternatives that are applicable to the embodiments of the present invention, which are defined and limited only by the scope of the invention.

1‧‧‧grinding roller
2‧‧‧Fixed rolls
3‧‧‧ moving roller
4‧‧‧Hydraulic cylinder
5‧‧‧Feed column
6‧‧‧Electric motor
6'‧‧‧Electric motor
8‧‧‧
9‧‧‧Compressed area
15‧‧‧The best working point

The invention is described in more detail with reference to the respective drawings: Figure 1 is a perspective view of one of the grinding rolls for ore; Figure 2 is a front view of one of the operating rolls; Figure 3 is the pressure between the rolls and the rolls Figure 1 is a relationship diagram between the motor torque and the pressure on the roller; Figure 5 is a relationship between the rotation of the roller and the motor torque; Figure 6 is a relationship between the motor torque and the gap between the rollers .

1‧‧‧grinding roller

2‧‧‧Fixed rolls

3‧‧‧ moving roller

4‧‧‧Hydraulic cylinder

5‧‧‧Feed column

6‧‧‧Electric motor

6'‧‧‧Electric motor

Claims (11)

A grinding roller (1) for ore, which is composed of two motors (6, 6'); a fixed roller (2) coupled to a reduction gear through a first cardan shaft and The motor (6); a moving roller (3) coupled to a reduction gear and the motor (6') through a second cardan shaft, the moving roller (3) being freely used for one of radial movements Provided; a hydraulic cylinder (4), which is mounted on the roller bearing housing and disposed perpendicular to a radial face of the moving roller (3), and configured to force it against the fixed roller (2); a feed column (5) disposed perpendicular to the two rolls (2, 3) directly above the gap defined between the two structures; wherein: the grinding rolls (1) have a control efficiency The components. A grinding roll (1) for ore according to claim 1 wherein: the means for controlling efficiency is configured to perform an ongoing measurement of the distance between the rolls (2, 3) and is made The automatic adjustment of this distance between the rollers (2, 3) can be corrected so that the distance remains equal to one of the previous adjustments. A grinding roll (1) for ore according to claim 1 wherein: the means for controlling efficiency is configured to maximize the torque provided by the motors (6, 6'). A grinding roll (1) for ore according to claim 1 wherein: the means for controlling efficiency is configured to maintain a constant ore level (8) in the feed column (5); The rotation of the rolls (2, 3) is disposed to make this control. The grinding roller (1) for ore according to claim 2, wherein: the automatic distance between the rollers (2, 3) is performed by adjusting the pressure supplied by the hydraulic cylinders (4) Adjustment. A grinding roll (1) for ore according to claim 2, wherein the measure of the distance between the rolls (2, 3) is changed from 3 mm to 12 mm. A grinding roll (1) for ore according to claim 3, wherein the power supplied by the motors (6, 6') is changed from 75% of its maximum power to 98%. A grinding roller (1) for ore according to claim 3, wherein: the automatic adjustment affects the torque provided by the motor (6, 6') and is provided by the hydraulic cylinder (4) by adjustment This pressure is performed. A grinding roller (1) for ore according to claim 3, wherein: the automatic adjustment affects the torque provided by the motors (6, 6') and by adjusting the rollers (2, 3) This rotation is performed. A grinding roller (1) for ore according to claim 3, wherein: the automatic adjustment affects the torque provided by the motor (6, 6') and the rotation of the roller (2, 3) is simultaneously adjusted And the pressure provided by the hydraulic cylinders (4) is performed. A method for obtaining the maximum efficiency of a grinding roller (1), characterized in that the following steps are performed: i) using a solid stopper to establish a minimum distance between the moving roller (3) and the fixed roller (2); Ii) determining a set point of the operating gap, which should be the same optimum operating point (15) of the press (1); and iii) automatically controlling the pressure generated by the hydraulic cylinder (4) until the operation is achieved The set point of the gap; iv) once the operating gap reaches the set point, the pressure is no longer changed.